The invention relates to an aircraft auxiliary power unit (APU), and more particularly the invention relates to a focalized APU mounting assembly and method for installing and removing the APU from the tailcone section of the aircraft.
An aircraft such as a commercial passenger jet typically includes an auxiliary power unit (APU) in the aircraft""s tailcone section. The APU is used to supply electrical power to systems and components while the aircraft is parked on the ground, in flight and during aircraft taxiing or landing. The systems and componetry may include for example kitchen appliances, in flight entertainment systems and instrumentation. The APU is generally comprised of a compressor which is operatively connected to a generator to drive the generator. The generator produces the electrical power required to drive the systems and components.
Prior art APU assemblies are suspended from the tailcone ceiling by a complicated matrix of struts and/or support members. The struts are typically several feet long and are of considerable weight. An APU assembly can weigh anywhere between one hundred (100) pounds for smaller aircraft up to one thousand (1000) pounds for larger aircraft.
In order to service or repair the APU, the unit must be removed from the tailcone section. Frequently, in order to gain access to the APU the tailcone must first be disconnected from the fuselage. The tailcone section can extend multiple stories in height. Once the tailcone has been removed, a number of technicians are needed to remove the Auxiliary Power Unit from the tailcone section. To this end, typically a first technician operates a small crane that supports the APU while one or more additional technicians disconnect the APU from the matrix of struts and support rods. The technicians then remove the APU from the tailcone section. When it is necessary to reinstall the APU in the tailcone section, the technicians reverse the process. The prior art method for and removing and installing an APU can take considerable time and during the time the APU is being serviced the plane is grounded.
The foregoing illustrates limitations known to exist in present APU devices and methods for removing and installing APUs in an aircraft tailcone section. Thus, it is apparent that it would be advantageous to provide an alternative directed to simplifying the method for removing and installing the APU and decreasing the time and number of technicians required to remove and install the auxiliary power unit. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.
In one aspect of the present invention this is accomplished by providing an aircraft auxiliary power unit that is supported by a focalized suspension system. The APU may be supported by a suspension system located underneath the APU or above the APU. The suspension system may also be a semi-focalized system. When the suspension system is located below the APU, the APU is supported by a bed with the focalized mounts made integral with the bed. If the system is located along the ceiling, the APU is suspended downwardly from the support members attached to the ceiling.
In either suspension configuration, the APU may be easily removed from and installed into the tailcone as a result of the system of the present invention. As a result of the system the APU may be removed quickly by a single technician. By the mounting assembly of the present invention, removal of the APU from and installing the APU into the tailcone section of the aircraft may be accomplished without first disconnecting the tailcone section from the fuselage. Thus by the present invention APU removal and installation can be achieved in significantly less time than if current methods and systems are used. As a result, a plane is grounded for a minimum period of time.
The system support members may include alignment members to readily locate the APU in the desired location and at the desired orientation. The alignment means may be comprised of nestable frustoconical members. The mounts supporting the APU may be comprised of a plurality of sandwich mounts. Alternatively the support system may be comprised of a number of mounts supported by first and second pylon members and a third mount that includes spherical bearing members between the mount and attachment points along the APU. The spherical bearing members accommodate small APU displacements due to changing ambient conditions such as significant temperature fluctuations.
The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures.